(1) Field of the Invention
The present invention relates to a pneumatic motor for providing linear movement. In particular, the present invention relates to a pneumatic motor for use in a linear motion conveyor. Linear motion conveyors, also known as differential impulse conveyors, move objects along a surface or tray by varying the direction and speed of the movement of the surface. The conveyor motor moves the conveyor surface slowly in a forward direction to convey the objects forward. The conveyor motor then moves the conveyor surface quickly in the opposite or backward direction. As the conveyor surface is quickly moved backwards, the objects slide along the conveyor surface such that the objects remain in the forward position. The slow forward and fast rearward motion is repeated to move the objects along the surface in the forward direction.
(2) Description of the Related Art
The related art has shown various piston systems for use in conveyors. Illustrative are U.S. Pat. Nos. 2,214,755 and 2,289,942 to Tafel; U.S. Pat. No. 5,402,878 to Lutz; U.S. Pat. No. 5,996,773 to Gist; and U.S. Pat. No. 6,026,949 to Foster.
The Tafel patents disclose a reciprocating conveyor where one (1) end of a piston is used to move the conveyor. The piston is driven by a hydraulic drive unit. The hydraulic drive unit is actuated by a motor. The actuating fluid for the hydraulic unit and piston is preferably oil. The reciprocating movement of the piston is controlled by the hydraulic drive unit.
Gist describes a fluid drive system for use to operate a reciprocating floor. The fluid drive includes an array of hydraulic motors where a piston is driven reciprocally within a cylinder by selective application of fluid under pressure to one (1) side or the other of the piston. Only one (1) end of the piston is used to move the floor.
Lutz and Foster describe a reciprocating slat conveyor having hydraulic drivers.
Only of minimal interest are U.S. Pat. No. 2,861,548 to Burgess, Jr., et al.; U.S. Pat. No. 3,704,651 to Kupka and U.S. Pat. No. 5,070,769 to Fehr.
Burgess, Jr., et al. describes a vibrator for use in a vibration conveyor which uses a reciprocating piston driven by fluid pressure such as compressed air.
Kupka describes a free piston vibratory power source for use in underwater applications which uses compressible fluids, such as compressed air or steam.
Fehr describes a pneumatic linear vibrator which uses a compressed air piston.
There remains a need for a simple and durable pneumatic engine which uses a piston moved by compressed air where the ends of the piston rod are used to provide the linear movement such as to move a reciprocating conveyor.